1. Field of the Invention
The present invention relates to optical fiber connectors.
2. Description of the Related Art
FIG. 12 shows an optical fiber connector. A ferrule 21 is held by a ferrule holder 22 which is housed in the receiving cavity 3 of a connector case 1 such that its bosses 23 and 24 are housed in channels 4 and 5 of the connector case 1 respectively.
FIG. 13 shows another optical fiber connector. A connector case 1 is provided at the rear end with a cable receiving aperture 2, into which an optical fiber cable 11 is inserted and secured to the connector case 1 by a threaded nut 12. An optical fiber 13 extends forwardly from the end of the cable 11 and terminates at a ferrule holder 22 which holds a ferrule 21 at the front end. The connector case 1 is provided at the front end with a receiving cavity 3 for housing the ferrule holder 22. The ferrule 21 extends forwardly in a front opening 8 of the connector case 1. A pair of arms 9 extends rearwardly from opposite sides of the connector case 1 for engagement with a mating plug.
In FIG. 14, the ferrule 21 is held by the ferrule holder 22 which is housed in the receiving cavity 3. The ferrule holder 22 is provided at the front end with a conical boss 25 with a flange 26 and at the rear end with a rear front flange 27 which abuts on an end clip 29. A coil spring 28 is placed between the flanges 26 and 27 for biasing the conical boss 25 forwardly so that the corner portion 25a abuts on the aperture 7 of the connector case 1 while the flanges 26 and 27 abut on the inside walls 3b and 3a of the receiving cavity 3, respectively.
In the connector of FIG. 12, however, the gap between the ferrule holder 22 and the receiving cavity 3 is so small that when the ferrule 21 is fitted into a precision sleeve 30, a small radial offset between the ferrule and the precision sleeve 30 causes a collision between them. As a result, the ferrule 21 is pushed rearwardly so that the rear end 22a of the ferrule holder 22 is pushed against the end wall 22a of the receiving cavity 3, producing a friction resistance in proportion to the pushing force. This friction resistance restricts the radial movement of the ferrule 21, making it very difficult to fit the ferrule 21 into the precision sleeve 30.
In the connector of FIG. 13, however, the corner portion 25a of the conical boss 25 abuts on the aperture 7 of the connector case 1 with little or no play so that even when the ferrule 21 is pushed rearwardly upon fitting into the precision sleeve 30, it hardly moves in the radial direction, making it very difficult to fit the ferrule 21 into the precision sleeve 30.